[Kotlin] Wrong array of objects code generation

Description

Kotlin class generation is broken for specific .yaml shown bellow, but works correctly for Swift4. An arrayOf is not object at all and does not exists.

Swagger-codegen version

2.4.2

Swagger declaration file content or url

"swagger": "2.0"

Activities:
    type: array
    items:
      $ref: '#/definitions/ActivityItem'

ActivityItem:
    type: object
    required:
      - date
      - water
      - rest
      - food
    properties:
      date:
        type: string
        format: date-time
      water:
        type: number
      rest:
        type: number
      activity:
        type: number
      food:
        type: number

Generates this corrupt kotlin file

import io.swagger.client.models.ActivityItem
import io.swagger.client.models.arrayOf

/**
 * 
 */
data class Activities () {}

Swift4 same file correct generation

import Foundation

public typealias Activities = [ActivityItem]

Command line used for kotlin generation

swagger-codegen generate -l kotlin -i swagger.api.yaml -c swagger-codegen.config.json -o my_directory

Command line used for swift4 generation

swagger-codegen generate -l swift4 -i swagger.api.yaml -c swagger-codegen.config.json -o my_directory

Suggest a fix/enhancement

your parser is missing test for array of objects but i am not quite sure if it should look like this typealias also for kotlin typealias Activities = Array<ActivityItem>

Run the provided swagger-codegen Kotlin command with the included Swagger YAML and inspect the Kotlin generation path that handles the Activities array schema. Compare the generated output with the Swift4 result and establish regression coverage; done means valid Kotlin represents Activities as an array of ActivityItem without the nonexistent arrayOf import.